In the nature of background for practical application of the present invention, reference is made to the system shown in FIG. 6. That Figure shows a recorder with a cutter for cutting roll paper. Therein symbol "1" denotes a key part of a single-pass type color plotter of an electrostatic recording - wet type developing system. The electrostatic recording roll paper 2, which is wound around a winding core 2a, is rotatably supported on a roll paper supporter 3. It has a width of 914 mm according to Japanese Industrial Standard AO, for example, and is rotatably supported on a support member not illustrated herein.
The roll paper 2 is drawn from the winding core 2a and is transferred to an upper cover unit 5 by a feeder. A roll paper path between the roll paper 2 and feeder 4 is provided with a cutter 6, a black recorder 7B, a cyan recorder 7C, a magenta recorder 7M and a yellow recorder 7Y in that order. The black recorder 7B is made from multi-needle electrode rows and consists of a recording head 7a for prescribed dot-shaped charge of roll paper, a pad 7b for giving a prescribed pressure for pressing the roll paper against the head 7a, a developing container 7c for storing developers including black toner for blackening, a developing roller 7d for feeding developers to the recording side of the roll paper and a cleaner 7f for removing the excess developers attaching to the non-recording part of the development-completed roll paper. The construction of cyan recorder 7C, magenta recorder 7M and yellow recorder 7Y differ from that of the black recorder 7B only in that the former store a developer containing a blue-coloring cyan toner, a developer containing a red-coloring magenta toner and a developer containing a yellow-coloring yellow toner.
The feeder 4 consists of a feeding roller body 4a around which roll paper can be wound, driving means (not illustrated) for driving the roller in the paper feed direction indicated by the arrow (a), and a pinch roller 4b for pressing the roll paper against the feeding roller body. The roller body 4a is supported rotatably on the upper cover unit 5 and the pinch roller 4b is received by the front cover 4d and is supported on the plotter body by a shaft 4c so as to be capable of swinging.
When the recording signal based on recording information is supplied from a controller (not illustrated herein) to the recording heads 7a of the recorders, they electrically charge the roll paper 2 in accordance with the color signal to form a dot-type electrostatic latent image. The latent image is brought to visualization by the toners of varied colors when the roll paper, which is fed while the feeding roller body 4a is running, enters the developing roller 7d. That is, roll paper 2 forms a colored picture after passing the recorders once. When recording pictures are formed on a part with a prescribed length of the roll paper, it is cut at prescribed points by a cutter 6.
As published in the gazette of Japanese Utility Model No. 7079/1978, etc., some cutters consist of a fixed blade whose length is a little longer than the cutting length of the work to be cut and of a movable blade having substantially the same length as the fixed blade and rotating in press contact therewith to cut roll paper. Also known are cutters whose rotary blade is run while being rotated in contact with the fixed blade.
The first of the above-mentioned cutters requires troublesome setting of the cutting work (e.g. roll paper) since it is necessary, between the fixed and movable blades and the structure, to maintain rigidity of the fixed and movable blades. This becomes complicated and bulky since increase in length of the blades naturally results.
This first prior art reference, though facilitating setting of cutting work, requires a long fixed blade which requires being given a structure for securing its rigidity when the cutting length is large and a steady decrease in its cutting property occurs since the fixed blade wears more rapidly than the rotary blade.
An object of the invention, therefore, is to provide a cutter which facilitates setting of the cutting work, maintains a cutting property over a long period and has a simple structure for securing its rigidity in cutting large-length cutting work.
In accordance with the invention, a cutter for cutting sheet material such as paper comprises a first driving cup-like rotary blade having a first circular cutting edge and a second driven cup-like rotary blade having a second circular cutting edge. The first and second cutting edges overlap over a predetermined arc and are in operative engagement with one another. First driving means are coupled to the first rotary blade to cause rotational movement of the first rotary blade. Means are included to bias the first and second cutting edges toward each other to engage and cut sheet material between the cutting edges and to cause the driven blade to rotate in response to rotation of the driving blade. The cutting points of the first and second blades continuously vary as the blades rotate so that the entire cutting edge of each the blades performs a cutting function during rotation of the blades.
Also in accordance with the invention, a cutter for cutting sheets of material, paper and the like comprises a cup-type main rotary blade supported by a main rotary shaft and having an edge part for performing cutting, driving means coupled to the main rotary shaft for rotating the rotary shaft in the work cutting direction and a cup-type sub-rotary blade, which is rotationally responsive to rotational movement of the main rotary blade, having an edge part for performing cutting and being rotatably disposed to face the main rotary blade. Also included are holding means for rotatably holding the main and sub-rotary blades so that the respective edge parts face each other in an overlapping manner and press-contacting means for bringing the edge parts of the main and sub-rotary blades into press contact to form a cutting element having constantly varying cutting portions during cutting action.
The invention will more fully be understood by reference to the following description taken in conjunction with the accompanying drawings. The scope of the invention will be pointed out in the appended claims.